Final answer:
To determine the minimum number of amino acid residues in the shortest alpha helix that can span a membrane bilayer, divide the width of the membrane by the distance between each turn of the helix.
Step-by-step explanation:
In integral membrane proteins, alpha-helices can span the membrane bilayer. Each helical turn in an alpha helix has 3.6 amino acid residues, and the distance between each turn of the coil is 5.4 Å.
Therefore, to calculate the minimum number of amino acid residues required for the shortest alpha helix that can span a membrane bilayer, we divide the distance across the bilayer (width of the membrane) by the length of each turn:
Minimum number of amino acid residues = width of the membrane / distance between each turn
Since the exact width of the membrane is not specified, we cannot provide a specific number of amino acid residues. However, this calculation allows you to determine the minimum number of residues needed for any given width of the membrane.